Neutron imaging of a commercial Li-ion battery during discharge: Application of monochromatic imaging and polychromatic dynamic tomography

A commercial lithium-ion polymer battery of prismatic construction was imaged in 2D by monochromatic neutron radiography at wavelengths around a LiC6 spectral feature. Over the range of 3–4 Å, the neutron attenuation spectra for charged and discharged batteries are distinctly different. In a real-time experiment, a battery was observed during discharge at wavelengths spanning the LiC6 spectral feature and its disappearance monitored. No evidence of “staging” was detected in this preliminary experiment. A similar battery was imaged in 3D with a new tomographic data acquisition scheme based on the Greek golden ratio; the scheme allows convenient post-processing to establish “time windows” for 3D image reconstruction. The 3D images at 5% state of charge intervals are compromised by beam hardening, but still show some asymmetric battery volume change with discharge. Finally comments on the future of neutron imaging for battery experiments, whether at continuous sources at nuclear reactors or at pulsed spallation sources, are discussed.